Comparison of three real-time pcrs for the quantification of CMV-DNA on dbs

BRIEF INTRODUCTION The Dried Blood Spot (DBS) is a useful sample for diagnosing congenital CMV infection (cCMV). Some authors suggest that a high viral load in blood samples could have an unfavourable prognostic value. In this study we compared the performances of three methods in measuring CMV viral load in DBS. MATERIALS AND METHODS We tested 36 DBS samples from QCMD panels (2006-2009). Purification of DNA was performed with a commercial kit (QIAGEN), following the DBS protocol. Viral DNA was quantified by means of an in-house method (gB gene) and two commercial kits “CMV, HHV6, 7, 8 R-gene”, Argene (for CMV: ppUL83) and “Q-CMV Real-time Complete kit”, Nanogen (MIEA). CLINICAL CASES OR SUMMARY RESULTS Intra- and inter- assay viral load values were within ±0.5log10 unit. All DBS prepared with whole blood spiked with 1E+02 copies/ml of CMV-DNA tested negative, while those with viral loads of 1E+03 copies/ml gave positive results in about half of samples. CONCLUSIONS The results obtained in this study are similar to datasets submitted by QCMD participants. All three methods detect equally high viral loads in DBS but they should be improved to identify also lower ones. The “CMV, HHV6, 7, 8 R-gene” kit seems to be particularly interesting, as it provides a readyto- use and cheap mix which permits also the simultaneous detection of different herpesviruses.